1. Field of the Invention (Technical Field)
The present invention relates to deployment of fins on projectiles.
2. Description of Related Art
A guided projectile, as opposed to standard dumb projectiles, requires the use of tail fins to stabilize the round during flight. In order to limit storage space and gun barrel damage, it is important that the fins remain stowed until the projectile has effectively cleared all aspects of the gun tube. Typically the retention and release of these fins has been accomplished using electro-mechanical or pyrotechnic mechanisms that can be costly to install and time consuming to ruggedize to the gun blast environment and reduce overall system reliability.
A key in projectile design is the need to provide stable flight with precision accuracy. To accomplish this historically, those of ordinary skill in the art have utilized active canards as the primary control surfaces and tail fins for stabilization. The common problem with canards and fins is retention prior to gun launch and release after the projectile has left the gun tube. Where the canards typically have electro-mechanical devices inherent in their design, tail fins typically do not and often require additional weight in the form of electronics or even dangerous pyrotechnics in the tail/warhead section. Patents illustrative of the state of the art include U.S. Pat. No. 7,104,497, to Johnsson, U.S. Pat. No. 6,880,780, to Perry et al., U.S. Pat. No. 4,175,720, to Craig, and U.S. Pat. No. 4,143,838, to Holladay.
The present invention allows one to eliminate the expensive electronics and dangerous pyrotechnics needed in the tail/warhead section of the projectile by providing a reliable and purely mechanical means of retaining and releasing a projectile's fins.
While U.S. Pat. No. 7,083,140, to Dooley, uses a contact pawl system towards the rear of the fins, the present invention uses a non-contact pawl system at the front of the fins. Dooley's system requires a significant cut in the fin, significantly reducing fin strength, and the present invention does not. Dooley also utilizes the pawl to deflect the fins outward, whereas the present invention does not. The present invention is much more compact than Dooley's in that his device extends from in front of the fins to nearly the aft pivot pin location and the present invention is located only at the forward end of the fins. Furthermore, Dooley's system will only work with forward folding fins and the present invention can work with either forward or rearward folding fins.